1. Field of the Invention.
This invention relates in general to a circuit for operating display elements, and more particularly, to an integrated circuit having selectable multiple display blink schemes or truths with a minimum of external components.
2. Description of Related Art.
This invention provides for the selection of multiple display blink schemes for conveying information about the operation of an integrated circuit. In the marketing of highly-integrated, application-specific integrated circuits, it is becoming increasingly difficult to target the needs of all customers. To successfully sell a product in today's competitive marketplace, a chip manufacturer must create a distinct "feel" to their product through its form and function. Manufacturers of system level products try to distinguish their product from a competitor's by appearance and function. As levels of chip integration increase, this becomes harder and harder to do for a system designer.
One way of creating a distinct "feel" to a chip is to design in flexibility. An integrated circuit manufacturer can attempt to anticipate all of the demands of its customers by designing multiple modes of operation into their chip. These modes are usually selected through configuration pins which are dedicated to mode selection. Thus, some pins may be used for mode selection during normal operation of the chip. On many highly integrated devices there are very few pins left unconnected or not used for some input or output function. Hence it is often times difficult to justify the tradeoff between functional pins and configuration pins.
In some of these types of chips, LEDs are used to convey information to the user. Accordingly, it would be useful for a system designer to distinguish their product by altering the LED blink scheme. Further, it would be desirable to have a mode selection pin which may be configured to change the truth table of the LEDs, i.e., how they blink to indicate the various operational conditions.
Further, a single LED can be used to display three different states: on, off or blinking. Thus, a dual LED can display a large amount of data using only a single pin of an integrated circuit (IC) as described in Application Ser. No. 08/271,111, filed Jul. 6, 1994 (U.S. Pat. No. 5,166,129), herein incorporated by reference. Trying to visually interpret all the information present, however, is difficult as it is possible to encode up to five states with a dual LED. Each user of the integrated circuit might also want to distinguish their product by changing the manner in which data is displayed to the user.
It is accordingly desirable to have an arrangement where multiple LED truth table schemes can be used with the integrated circuit device without reconfiguring the IC device or providing unique devices for the different situations.
It can be seen that there is a need for multiple blink schemes designed into an IC.
It can also be seen that there is a need for providing the selection of an LED blink scheme using external signals.
There is accordingly a need to provide a system for operating with a different number of display modes and yet be efficient from a logic and circuitry perspective.